UAVs make bridge inspections and other tasks faster and safer.
Public works departments across the country are embracing drones on a variety of projects, from landscape analysis and surveying to water main repairs, bridge inspections and roadway construction.
“It’s the future of civil engineering,” said Greg Parker, Johnson County Engineer for Johnson County, Iowa, where he and his team of 47 workers are responsible for construction, engineering and maintenance of 940 miles of roads and bridges. An FAA-certified drone pilot, he’s enthusiastic about integrating UAVs into the county’s workflow, partly due to the “cool factor.”
“Drones are renewing interest in the field,” he said. “The younger crowd wants to study engineering so they can use this technology on the job.”
Saving time and money
The number one reason drones are finding a home in public works, Parker said, is that they save time, money and manpower. “Old school, you take a crew out to survey a project. Now, you take a drone out and fly it and get the same if not better data, all on a shorter timeline and with fewer workers.”
The city of Spokane, Washington, seems to agree. Late last year, the Spokane Public Works Department got permission to purchase its own fleet of drones, which it plans to use to perform infrastructure inspections, monitor project progress and conduct landscape and environmental analysis.
Many other public works departments are also flying drones. In fact, according to a survey from the American Association of State Highway and Transportation Officials, at least 35 state departments of transportation are adopting drones in the field, with at least 20 states using them daily for tasks like monitoring roadway construction, performing pavement inspection, monitoring traffic control and inspecting high-mast light poles.
A number of state DOTs use drones for bridge inspections. The Minnesota Department of Transportation, for example, has been experimenting with drones for bridge inspections since 2015. That’s not surprising when you consider that the state is home to some 20,000 bridges, and that bridge inspections are quite dangerous for human inspectors. Operating drones in confined spaces — such as between beams in the case of multibeam bridges — can be tricky, so MDOT selected a commercial drone that was highly “collision tolerant.” It’s enclosed within a spherical cage so that even direct contact with bridge elements can’t damage the rotors or cause a crash.
Now is an especially good time for municipalities to invest in drones. Parker said that you can acquire a complete drone system — including the UAV, controller, and software to process and import the data into other applications such as AutoCAD — for about what GPS equipment would have cost five or ten years ago.
“There are places where it's simply dangerous to send people. Instead, now you can fly a drone up — say, between two beams at a very high elevation off the water — take pictures, and if it all looks good, there's no need to send people up there to do a physical inspection.”
Benefits for inspectors and drivers
By leveraging drones, county engineers can accomplish more with greater safety and less interruption to the day-to-day use of infrastructure. For example, Parker explained that drones equipped with infrared cameras can be used to inspect bridge decks for delamination, a common problem caused by factors including deicing salts, freeze-thaw cycles and rebar corrosion.
“Traditionally, the only way to truly see where there's delamination is to drag a chain across it,” he said. “Now you can fly a drone up there even when there's still traffic moving across the road, scan the deck, and see where the delamination is.”
If the drone reveals indications of a problem, Parker noted, you can take a crew to the site, shut down the affected lanes and drag a chain for a detailed analysis. But if the drone doesn’t see a problem, you can avoid inconveniencing drivers.
Drones are also keeping workers out of harm’s way. “There are places where it's simply dangerous to send people,” said Parker. “Instead, now you can fly a drone up — say, between two beams at a very high elevation off the water — take pictures, and if it all looks good, there's no need to send people up there to do a physical inspection.”
Moreover, drones can sometimes see into places that are difficult or impossible for humans to reach, making the inspection more thorough.
Parker’s due diligence has convinced him that the data he gets from drones is as good as the old-fashioned alternative. “On a few projects we sent a survey crew back out to confirm that the data the drone gathered was correct.” But that doesn’t mean drones can, or will, ever completely replace human crews.
“It’s a great tool to have at our disposal, but we evaluate every project to see what’s best,” he said. “There’s always going to be a need to send crews out to the site. But as we get further into the future, I think you’ll find there will be a switch and we’ll use drones more often than crews.”
Dave Johnson is a Los Angeles-based freelance writer who has been writing about all aspects of business and technology since before there was an internet.